Lindor Gingerbread Thumbprint Cookies

Preheat oven to 350ºF (175ºC). Line two baking sheets with parchment paper.
With a sharp, serrated knife, carefully slice the Lindor Gingerbread Truffles in half, and then place them in the freezer for an hour.
Whisk together all-purpose flour and salt in a medium bowl. Set aside.
In the bowl of an electric mixer fitted with the paddle attachment, cream together butter and sugar until light and fluffy, about 2 minutes. Scrape down the bowl and beater, turn mixer to low, then add egg yolk, then vanilla. Scrape down the sides of the bowl as needed.
Add dry ingredients to mixer bowl and mix on low. Increase mixer speed to medium and beat until a smooth sugar cookie dough forms.
Divide dough into 12 pieces. Roll into round, smooth balls and place on prepared baking sheets, spacing them 1.5 inches (4 cm) apart. Press centre of each ball with your thumb (or the handle of a wooden spoon) to create a wide and deep indent.
Bake for about 12 to 14 minutes, until edges just begin to turn golden brown. Let cool 5 minutes on baking sheet (press down indentation if it has puffed), then transfer cookies to a wire rack. Let cool 2 more minutes. Take Lindor halves out of the freezer, and press into each indent. Let cool completely.